One knows from CH-153246 a time piece with jumping hours comprising an hour disc in which the hour ciphers may be cut out under the aperture of the dial showing the hour cipher, this disc comprising two zones of different colors. This day/night disc is indexed of half a turn at six o'clock in the evening and at six o'clock in the morning to modify the appearance of cipher located in the aperture of the dial indicating if it is an hour of the night or of the day.